The pipe must be diverted by an RGI with LPG qualifications.
Do not let the builder get within half a mile of it.
Yes there are loads of regulations, and I'm not about to tell you.
Get an RGI as above.
First if anyone hasn't picked on the fact.
We are talking LPG, That would be 6BAR pressure up to the second stage regulator.
The pipe is almost certainly the property of the supplier.
If the builder or anyone else that's not competent to work on high pressure gas touches it, then it's Riddor reportable and trust me when I say it's immediately dangerous.
The pipe can come out of the ground before the extension into the second stage regulator, and from there it can go into the building above ground.
And that is all the information you or anyone needs to know.
Terrible thing, Ego.